By some comparisons, it's considered a "small" breach. But it's still potentially deadly to a lot of people.

IRS officials say they will be contacting citizens who's identity and information was part of a breached program that hackers were able to infiltrate and steal data.

The IRS says hackers (and clever ones at that) were able to access a program called "Get Transcript" where taxpayers can access and get copies of past tax returns and other personal tax data from previous years.

Thieves were able to infiltrate the program, and IRS officials say the data of over 100,000 people was potentially compromised.

The IRS wouldn't say if the data breach contained enough information for the hackers to access those people's actual tax returns.

The IRS says it will offer credit monitoring to those who's information was potentially affected.

According to CNN Money Tuesday:

"An unnamed cybermafia used this app to download forms full of personal information. They posed as legitimate taxpayers, and tried to download forms on 200,000 people between February and May. They got away with half of them, the IRS said.

The crooks used about 15,000 of them to claim tax refunds in other people's names.

But the potential damage is worse. IRS Commissioner John Koskinen said he believes the criminals' true mission was to gather vast amounts of personal information. Armed with that info, fraudsters can open bank accounts, credit lines and steal tax refunds in the future."

Koskinen described it as "not" your typical hacker attack.  This appeared to be a very sophisticated assault using state-of-the art equipment, and obviously operated by very smart savvy criminals.  It's one of, if not the most, complicated attacks on IRS data ever.

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